Reply
Trusted Contributor
Trusted Contributor

Re: 3608 Oil sampling location

Dwight,

Congratulations on your knowledge milestone.  One can never learn too much; it will all help.

 

I appreciate the opportunity to converse with you about Cat gas engines.  I am always glad to help a person find answers to questions they, although there are times when the answers are not easily found.

 

Good luck on your work activities.  Be safe.  Thanks.

 

Best Regards,

Al Hunt

Contributor

Re: 3608 Oil sampling location

If I can ever figure out why it turned black I will pass it along.  I just finished up and passed my ICML - Machinery Lubication Analyst Level 1 training and testing.  That is why I was also surprised why they were told to sample the oil from the crankcase. 

Trusted Contributor
Trusted Contributor

Re: 3608 Oil sampling location

Dwight,

Thanks for the update.  I am a bit surprised however by some of your comments.  Cat has been in the oil analysis business since beginning in 1970.  They began with a controlled and dealer managed fleet of over 100 pieces of Cat equipment.  The customer did nothing but run the equipment; all maintenance and repairs was performed by the Cat dealer in concert with the Cat oil analysis people.  And they learned a lot during this beginning.

Almost from the beginning, Cat has always recommended a "live sample" for the most representative sample.  Here is what the "How to take a sample brochure" states: 

It is recommended that pressurized systems without sampling

ports be fitted with sampling port kits. For pressurized systems,

this provides the most reliable sample. If a pressurized system

does not have a sampling valve, follow the vacuum extraction

method described below.

And Cat dealers follow Cat recommendations on this recommendation.  So I am surprised that someone at Wagner recommended taking the sample from the crankcase.  I don't think that Marianne Long, Wagner's lab manager would agree with that either.  I was responsible for a dealer oil lab for nearly 10 years and I never heard anyone at Cat make the recommendation of a sample from a static sump like a crankcase instead of taking a sample from a pressurized tap.  Our experience is that there is a much greater risk of not getting a reliable sample from the static compartment than from a pressureized tap.  Anyway, that is minor at this point, I think.  I also believe in not arguing with someone's success, if it works.

I still am surprised and intrigued by what you found in your photos.  From my experience, I think what your results were are an exception and not the rule that the many people involved in oil sampling have found over the years about the reliability of taking a sample from a pressurized tap, if possible. 

 

I will be interested in any future activities that you have in this search for a real answer that you can document about the blackening of the oil.  I just don't have an answer from what you have shared with me.  Again, thanks for sharing with me.  I always learn something during an exchange of ideas and experiences.

 

Best Regards,

Al Hunt

 

Contributor

Re: 3608 Oil sampling location

Latest update: Operations has decided not to flush the engine because we aren't having any actual wear metal show up in the oil analysis reports.  Somone at Wagner Cat informed them that they should be sampling oil from the crankcase.  They did and sent it in for analysis and it came back with a lower ISO number than the fresh oil.  I went and took some small samples from the thermostat housing, the crankcase, and the fresh oil.  I put them on a 5 micron patch and washed the oil off leaving behind anything larger than 5 microns.  I then used my cell phone to take these pictures through a cheapo 120X microscope.  I will be using these pictures to help explain why that isn't the best place to sample the oil.

 

1. Oil from the thermostat housing

2017-05-04 Creston Engine Oil sample picture SMALL.jpg

 

2. Oil from the crankcase

2017-05-09 Creston Crankcase Oil sample picture SMALL.jpg

 

3. Fresh clean unused oil

2017-05-04 Creston Clean Oil sample picture SMALL.jpg

 

Contributor

Re: 3608 Oil sampling location

Thanks, I will suggest that, but I first want to flush the engine and see what happens to the Pegasus 805.

Trusted Contributor
Trusted Contributor

Re: 3608 Oil sampling location

Dwight,

Cat does not recommend any commercial gas engine oil.  Cat decided many years ago to have a branded oil that meets the Cat gas engine requirements so that a customer could obtain a good performing in any part of the world, where sometimes good performing commercial oils for gas engines is not available.  Good performing commercial gas engine oils must meet a Cat designed 7,000 hour oil test that will allow a commercial oil supplier to prove that their brand of oil is an acceptable performer.  The field results are shared with Cat engineers and the commercial company is free to advertise the oil performance results.  However, Cat does not recommend any oil. 

There are a lot of good performing gas engine oils available besides Cat gas oil.  Mobil Pegasus 805 has been a good performing gas engine oil.  Mobil also has 905 and 1005 available, with the major difference being in the base stock oil.  There are many G3500 and G3600 engines running on Mobil Pegasus oil.

 

Since you have learned that another Cat gas engine seems to have the same blackish issue, let me suggest that you, for the sake of determining oil performance, why don't you try using Cat gas engine oil in this G3608 for a while and see if the blackening issue goes away.  It would only cost a bit more for the oil but it would give you an alternative for comparison. I have seen this done by other customers with some satisfaction and resolution has occurred.

 

If you hae any questions, don't hesitate to contact me.

 

Best Regards,

Al Hunt 

 

If you have

Highlighted
Contributor

Re: 3608 Oil sampling location

Turns out there is also a Cat 3412 genset using the same Mobil Pegasus 805 oil, and it's black.  Is that the oil that Cat recommends?

Contributor

Re: 3608 Oil sampling location

Thanks, that will simplify the flushing.  I'll go look for that line when I get a chance.

Trusted Contributor
Trusted Contributor

Re: 3608 Oil sampling location

The prelube pump suction is a hose that runs from the inlet of the prelube pump down to a connector on the big tube that is the suction to the main oil pump.  You could disconnect this from  the prelube pump and use it to supply the prelube pump from a barrel or container.  However, there is no manual shut off on the prelube pump suction line so the crankcase will have to be drained because all of the prelube suction line is below the crankcase level.  Cat never installed a manual valve in the thoughts that someone might accidentally leave it closed.

You could connect another clean pump to the connection where the prelube pump discharges on the lube oil piping.  This would feed oil into the engine passages.  The prelube pump does not have near as much flow as the main oil pump so it will not flow to the upper parts of the engine very quickly.  You also would want to be sure that there is no contamination from a separate container of oil.

Prelube Hose Discharge.jpg

Best Regards,

Al Hunt

Contributor

Re: 3608 Oil sampling location

At this point I'm pretty sure the oil turned black again becasue of the left over oil in the engine being diluted into the fresh oil.  We are looking at ways to flush the oiling system.

 

If I'm correct it looked like the main oil pickup in the crankcase feeds both the pre-lube pump and the main oil pump.  Is there a place where we could introduce the fresh oil to the pre-lube pump and use it to flush the engine without running the engine?